JPS59155540A - Electronically controlled fuel injection apparatus for engine - Google Patents

Abstract

PURPOSE:To simplify calculation of the injection quantity of fuel and to thereby lower the manufacturing cost of a fuel injection apparatus, by setting the injection quantity of fuel as the injection crank angle, and driving an electromagnetic fuel injection valve disposed in an intake system for the period of crank angle set by a crank angle signal. CONSTITUTION:In operation of an engine, outputs of an air-flow meter 26, a water-temperature sensor 27, etc. are furnished to a CPU29 after A/D conversion at 28, and the value K.Q is calculated by multiplying the quantity Q of intake air by a correction factor K read out from an ROM30 according to the operational conditions of engine such as the water temperature. Fuel injection is started by energizing a power transistor Tr34 and driving an electromagnetic fuel injection valve 35 by setting an FF23 each time a reference signal produced from a crank-angle sensor 21 is applied to the FF23. At the same time, a pulse counter 22 is cleared and the FF23 is reset when the count value of 1 deg.-signal produced by the pulse counter 22 and given to a comparator 32 becomes equal to the above value K.Q to terminate fuel injection by deenergizing the power transistor Tr34.

Description

[Detailed description of the invention] The present invention relates to an electronically controlled fuel injection device for an engine.

An example of a conventional electronically controlled fuel injection system for an engine will be outlined with reference to FIG. In the figure, the signal output from the crank angle sensor 51 every 1 degree of engine rotational crank angle is input to a pulse counter 2, which counts the number of signal inputs per unit time and converts the value to the engine rotation speed N. It is output as a signal to the arithmetic circuit 3.The output of the 6-air flow make 4 is converted into a digital intake air amount Q signal by the A/D converter 5 and output to the arithmetic circuit 3.The arithmetic circuit 3 is connected to the engine rotation From the number N and the amount of intake air Q, the basic injection amount Tp of fuel is calculated as a value proportional to the amount of air taken into the cylinder per revolution of the engine using the following equation.

Tp = K - Q/N Furthermore, by inputting various information detected on the state of the engine and each part of the vehicle, and multiplying by the correction coefficient read from the memory 6, the actual fuel injection amount T is calculated, and the signal is It is output to register 7 and temporarily stored.

On the other hand, a reference signal output from the crank angle sensor 1 every revolution of the engine is input to a counter 8 and a comparator 9. The counter 8 counts the clock pulses output from the clock pulse generator 10 and is reset every time the reference signal from the crank angle sensor 1 is input. When the reference signal is input, the comparator 9 turns on the power transistor 11, energizes the electromagnetic fuel injection valve 12 to start fuel injection, and compares the value of the register 7 (that is, the fuel injection amount T) with the value of the counter 8. When the value of the counter 8 becomes equal to the value of the register 7, the power transistor 11 is turned off and the electromagnetic fuel injection valve 12 is closed to terminate fuel injection.

In this way, the electromagnetic fuel injection valve 12 opens only for a period of time corresponding to the fuel injection amount T after the reference signal is issued.
Fuel is injected by a set fuel injection amount T every revolution of the engine.

However, with the conventional method of calculating the fuel injection amount as the injection time and controlling the injection amount by controlling the energization time of the electromagnetic fuel injection valve by measuring the absolute time, the calculation is complicated and the clock pulse is There was a problem in that a generator and the like were required, resulting in high costs.

The present invention has been made in view of these conventional problems, and provides an electronically controlled fuel injection device for an engine that simplifies calculation of fuel injection amount and reduces costs by eliminating the need for a clock pulse generator or the like. The purpose is to

For this reason, in the present invention, the fuel injection amount is based on the amount of air taken into the intake pipe, and a means is provided for correcting this to set the energization period of the electromagnetic fuel injection valve by the crank angle, and The above object is achieved by providing a means for energizing and driving the electromagnetic fuel injection valve for a period corresponding to the crank angle.

The present invention will be described below based on embodiments shown in the drawings.

In FIG. 2 showing one embodiment, a crank angle sensor 21
The signal output from the 1-degree crank angle is input to the pulse counter 22, and the reference signal output at every predetermined crank angle is input to the set terminal S of the flip-flop 23 and the input/output board 24 together with the pulse counter 22. be done. Further, a detection signal from the idle detection switch 25 is also input to the input/output port 24. On the other hand, air flow meter 2
Analog detection signals from 6, water temperature sensor 27, etc. are A/D.
The signal is input to a converter 28 and digitally converted. The input/output board 24 and the A/D converter 28 and C'P
U29. ROM30. The latches 31 are freely connected to each other for input and output. The latch 31 outputs a value corresponding to the fuel injection crank angle calculated by the CPU 29 as described later to the comparator 32. The comparator 32 outputs a reset signal to the reset terminal R of the flip-flop 23 when the value counted by the pulse counter 22 matches the value input from the latch 31.

The output of the flip-flop 23 is outputted to the Hose terminal of the power transistor 34 via the resistor 33, and when the power transistor 34 is energized, the electromagnetic fuel injection valve 35 is opened and fuel is injected.

Next, a series of operations of this configuration will be explained.

When the intake air amount Q signal, water temperature signal, etc. output from the A/D converter 28 are input to the CPU 29, the CPU 29
A correction coefficient K based on detected values of cooling water temperature and other various operating conditions is read from the ROM 30, a value obtained by multiplying the intake air amount Q by this correction coefficient K is calculated by -Q, and this value is applied to the latch 3.
Output to 1.

On the other hand, when the reference signal is output from the crank angle sensor 21, the flip-flop 23 is turned on, the power transistor 34 becomes conductive, and the electromagnetic fuel injection valve 35 is driven to start fuel injection. At the same time, the pulse counter 22
is cleared and counting of the 1° signal is started. Then, when the count value of the 1° signal outputted from the pulse counter 22 to the comparator 32, that is, the engine rotation and rank angle from the time when the reference signal was generated, matches the value outputted from the latch 31 with -Q, the comparator 32 A reset signal is outputted, thereby resetting the flip-flop 23 and turning off the power transistor 34, causing the electromagnetic fuel injection valve 35 to stop operating and enter the injection path (see FIG. 3).

Here, since the period of the 1" signal is proportional to the period 1/N of one rotation of the engine, the injection time, that is, the injection amount obtained by multiplying the 1° signal by -Q, can be set in the same way as before. -Q means that the injection period is expressed as a crank angle.

In this way, there is no need to perform calculations using the engine speed N as in the past, and the rotational crank angle signal can be used as is to control the injection time, so the clock pulse generator etc. It is no longer necessary and costs can be reduced.

Note that during deceleration operation determined by the ON signal of the idle detection switch 25 and the reference signal, the fuel injection amount is set to 0 and fuel injection is stopped.

As explained above, according to the present invention, the fuel injection amount is set as the injection crank angle, and the electromagnetic fuel injection valve is driven to inject fuel for the crank angle period set by the crank angle signal. Since the setting does not use the engine speed, it is simplified, and a pestle, clock pulse generator, etc. are not required, resulting in effects such as cost reduction.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a conventional electronically controlled fuel injection device, FIG. 2 is a block diagram showing an embodiment of the present invention,
FIG. 3 is a diagram showing signal waveforms of various parts of the device according to the above embodiment. 21...Crank angle sensor 22...Pulse counter 23...Flip-flop 2G...Air flow make 29...CPU 30...ROM
31...Lunch 32...Comparator 34
...Power transistor 35...Electromagnetic fuel injection valve Patent applicant Japan Electronics Co., Ltd. Representative Patent attorney Fujio Sasashima

Claims (1)

[Claims] Electronically controlled fuel for an engine that controls the fuel injection amount by energizing an electromagnetic fuel injection valve attached to the engine's intake system for a period set according to engine operating conditions at a predetermined rotational crank angle. In an injection device, a means for setting an energization period of an electromagnetic fuel injection valve by a crank angle by correcting based on a detection result of an air amount taken into an intake pipe of an engine based on other operating state detection results, and the means and means for driving the electromagnetic fuel injection valve with electricity for a period corresponding to a crank angle set every predetermined cycle.